The objective of this collaborative clinical research effort is to improve the care of patients with bladder carcinoma through studies of different aspects of clinical management. The studies are carried out in several institutions simultaneously according to well-designed protocols. A central laboratory is responsible for the uniform collection, classification and analysis of pathologic and cytologic material and all data are being collected, organized and analyzed in a central statistical office. In each participating institution, followup of patients entered into the following protocols is continuing: Surveillance of all patients admitted with bladder carcinoma; the study of multiple mucosal biopsies from patients with frank tumor and/or positive cytology; evaluation of different forms of intravesical therapy, invasive carcinoma, radiotherapy alone and preoperative radiotherapy following by cystectomy. The following protocols have been initiated: Studies of systemic chemotherapy in patients with metastatic bladder carcinoma; studies of adjuvant systemic chemotherapy in association with definitive therapy of invasive bladder carcinoma; and studies of intervention (secondary prevention) in patients with completely resected low-stage lesions. This application provides for central pathology services to this multi-institutional collaborative effort.